Blood nitrates content in patients with systemic lupus erythematosus and antiphospholipid syndrome

Aim. To elucidate clinical implications of nitrates (NO3) concentration as an indicator of nitric oxide (NO) level in blood serum of patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (PAPS). Material and methods. Blood serum concentration of NO3 was measured by high-performance liquid chromotography in a total of 41 patients with SLE (n=17), PAPS (n=14) and secondary APS (n=9). Sera from 10 healthy subjects (donors) served as control. NO3 concentration >40 mcmol/l was stated high. SLE activity was assessed by V.A. Nasonova's scale and SLEDAI index (SLEDAI >9 indicated SLE exacerbation). Patients with PAPS were divided into two groups depending on clinical symptoms: 7 patients with significant thrombosis or history of more than two thrombotic complications (group 1); 7 patients with the history of two or less thromboses (group 2). Results. The mean serum nitrate concentration in the SLE group was 43.59 mcml/l (range 17.06-113.22). The nitrate level of the sAPS+SLE group was 49.81+/-27.54 and did not significantly differ from APS (33.67+/-14.70). By univariate standard analyses, serum nitrate concentration was significantly higher in patients with high disease activity (5731+/-25.12 vs. 25.62+/-6.96, Mann-Whitney test, p<0.01). The Spearman correlation coefficient of nitrate level with SLEDAI was 0.8 (p<0.001). Conclusion. A nitrate level is increased in patients with active SLE and in APS patients with severe thrombotic complication.